Lifespan Extending Activity of Substances Secreted by the NematodeCaenorhabditis elegansThat Include the Dauer-Inducing Pheromone
32
Citation
14
Reference
10
Related Paper
Citation Trend
Abstract:
The nematode Caenorhabditis elegans yields a substance(s) inducing the larval diapause, called dauer-inducing pheromone. We discovered that the crude pheromone extract extends the adult lifespan in the animal. This extension does not occur in the mutant animal, in which expansion of the lifespan caused by other mutations reducing insulin signaling is suppressed. This is the first description concerning the relevancy of the pheromone to the longevity in the animal.The current study investigated the possible effects of static magnetic fields (SMFs) on the developmental and aging processes of Caenorhabditis elegans. Nematodes were grown in the presence of SMFs of strengths varying from 0 to 200 mT. The rate of development and the lifespan were recorded. Treatment with a 200 mT SMF reduced the development time from the L2 to the L3 stage by 20%, from L3 to L4 by 23%, and from L4 to young adult by 31%. After SMF treatment, the average lifespan was reduced from 31 days to 24 days for wild-type nematodes. The up-regulation of clk-1, lim-7, daf-2, unc-3 and age-1 after SMF treatment was verified by quantitative real-time RT-PCR. Apparently, induction of gene expression is selective and dose dependent. The total developmental time was significantly reduced for the lin-4, lin-14, lin-41 and lim-7 mutants, but not for the let-7, clk-1, unc-3 and age-1 mutants. Lifespan analyses revealed that the let-7, unc-3 and age-1 mutants were not affected by SMF treatment. Here we show that SMFs accelerate nematode development and shorten nematode lifespan through pathways associated with let-7, clk-1, unc-3 and age-1.
Developmental stage
Developmental Biology
Cite
Citations (21)
Laboratory studies were conducted to determine if Diabrotica longicornis (Say) has the potential to enter prolonged egg diapause and to quantify D. longicornis fecundity and longevity. The immature developmental periods of the sibling species, Di abrotica longicornis and D. barberi Smith and Lawrence were also compared. When fed a diet of zucchini squash, the mean fecundity of D. longicornis was 185.6 eggs per female and the mean longevity was 54.2 days. The immature developmental period of D. longi cornis (mean 43 days) was significantly shorter than that of D. barberi (mean 47 days) when both species were reared on corn. A small percentage of D. longicornis eggs hatched 15 days after oviposition, 44.2% hatched after one chill period, and additional eggs hatched after a second chill period. This suggests that nondiapause and prolonged diapause traits occur within the D. longicornis population studied. The northern corn rootworm, Diabrotica barberi Smith and Lawrence has re cently been separated from D. longicornis (Say) and elevated to species status based on morphometric and color variation, and differences in mating behavior, habitat preference, and sex pheromone response (Krysan et al., 1983). Other biological characteristics have been reported that separate the two species. Quan titative differences in cuticular hydrocarbon profiles exist between the species (Golden, 1990), and a specific esterase occurs in males of D. longicornis but not in D. barberi males (McDonald et al., 1982). Also, compared with D. barberi, eggs of D. longicornis are at a more advanced embryological stage when they enter diapause (Krysan, 1982; Krysan et al., 1983). The two species do share enough taxonomic characteristics to have been de scribed as sibling species (Krysan et al., 1983). The male genitalia and sperma thecae, which are generally useful in separating Diabrotica species, are so similar that they are not diagnostic for these species. There are also no visible differences in the egg chorion sculpturing (Krysan et al., 1983; Krysan, 1987), and there is an apparent allelism of allozymes in the two species (McDonald et al., 1982). D. barberi is an economic pest of corn and various aspects of its biology have been thoroughly studied. These include the effect of temperature on egg hatch (Apple et al., 1971; Chiang and Sisson, 1968; Patel and Apple, 1967), egg diapause (Chiang, 1965; Cunningham and Peters, 1964; Krysan et al., 1986), larval host specificity (Branson and Ortman, 1967, 1971), immature development (Domi nique and Yule, 1983), and reproductive development and longevity of females (Naranjo and Sawyer, 1987). To increase our understanding of the relationships of D. longicornis and D. barberi, D. longicornis biology and ecology are being studied. Because the two species appear to be closely related, learning more about D. longicornis may enhance our understanding of D. barberi and may help determine if D. longicornis has the potential to become an economic pest. This paper reports the results of Accepted for publication 29 October 1990. This content downloaded from 157.55.39.219 on Tue, 19 Jul 2016 06:04:38 UTC All use subject to http://about.jstor.org/terms 252 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY laboratory experiments that were designed to determine if D. longicornis has the potential to enter prolonged diapause, to compare the D. longicornis immature developmental period to that of D. barberi, and to determine the fecundity and longevity of D. longicornis females. Materials and Methods All D. longicornis originated from populations located in Dundy Co., Nebraska and all D. barberi originated from populations located in Cottonwood Co., Min nesota. Eggs were collected and F{ individuals from the field collected beetles were used in the laboratory experiments. Although the native larval host range is unknown for D. longicornis, the species has been successfully reared on seedling corn (McDonald et al., 1982). To deter mine and compare the developmental periods of D. longicornis and D. barberi from neonate larva to emerged teneral adult on field corn, larvae of both species were reared on seedling corn (Pioneer 3377). Corn seedlings were placed on moist peat (72.7% moisture by weight) in one-ounce covered plastic containers. A single neonate larva was placed in each plastic container and containers were held at 23 ? 0.5?C in a 15:9 (L:D) photoperiod. New corn seedlings were added as needed. The sex and developmental period of each individual were recorded as beetles emerged. The mean developmental periods (emergence recorded daily) were cal culated for both sexes of each species. T-tests were used to compare the devel opmental periods of the two species and the developmental periods of the sexes within each species. To determine the fecundity of D. longicornis females, ?x individuals from field collected beetles were reared as larvae on corn seedlings (Pioneer 3377). Twenty pairs were caged in individual polystyrene petri dishes (100 x 15 mm). Soil (<60 mesh size particles) was placed in one-half of each dish as oviposition medium. The soil was kept moist (34.8% moisture by weight) throughout the ovipositional period. The beetles were fed zucchini squash which was replaced every 2-3 days. Each beetle pair was held at 23 ? 0.5?C in a 15:9 (L:D) photoperiod until the female died. Results of preliminary experiments indicated that D. longicornis females would readily oviposit in the soil under these conditions (Golden and Meinke, unpubl.). Any eggs found on the food were removed with a fine sable brush and placed on the soil. Eggs were collected by washing the soil from each petri dish through a combination of Number 20 and 60 U.S. Standard sieves. The mean longevity period (in days) per female and the mean number of eggs oviposited per female were calculated. To determine if D. longicornis has the potential to enter extended egg diapause, 3350 eggs were obtained from D. longicornis females collected in Dundy Co., Nebraska. The eggs were initially held at 25 ? 1?C in a 16:8 (L:D) photoperiod for 12 weeks and the number of eggs that hatched during that period was recorded. The eggs were then held at 5 ? 1?C in complete darkness for 15 weeks. At the end of that period a subsample of 500 eggs was removed from the cold room and held at 23 ? 0.5?C in a 15:9 (L:D) photoperiod for 32 weeks. The number of eggs that hatched during this period was recorded. The unhatched eggs from the sub sample were again held at 5 ? 1?C and in complete darkness for another nine weeks. At the end of that period, the eggs were held at 23 ? 0.5?C in a 15:9 (L:D) photoperiod to determine if additional eggs would hatch. The temperature regimes This content downloaded from 157.55.39.219 on Tue, 19 Jul 2016 06:04:38 UTC All use subject to http://about.jstor.org/terms VOLUME 64, NUMBER 3 253 Table 1. The mean developmental periods from neonate larva to teneral adult of D. longicornis and D. barberi. Species N Sex Mean (days) ? SEM D. longicornis 29 99 43.72 ? 1.44a 20 66 41.50 ? 1.69 D. barberi 32 99 47.00 ? 0.89a 22 66 46.68 ? 0.87 D. longicornis 49 Pooledb 42.81 ? 1.09c D. barberi 54 Pooled 46.87 ? 0.63 a Within species, no significant differences between means (P < 0.05, Mest). b Sexes pooled prior to analysis. c Means between species significantly different at P < 0.01 (Mest). were selected based on previous studies of D. barberi diapause (Chiang et al., 1972; Krysan, 1982) in which 5-7?C chill (shown to be thermal optimum for maximum egg hatch) and 20-25?C warm periods were used.
Cite
Citations (9)
Summary The main food source of free‐living nematodes in the soil environment is bacteria, which can affect nematode development, fecundity and survival. In order to occupy a reliable source of bacterial food, some nematodes have formed specific relationships with an array of invertebrate hosts (where bacteria proliferate once the hosts dies), thus forming a tritrophic system of nematode, bacteria and insect or other invertebrates. We isolated 768 Bacillus strains from soil (from Germany and the UK), horse dung and dung beetles and fed them to the genetically tractable free‐living nematodes Caenorhabditis elegans and Pristionchus pacificus to isolate nematocidal strains. While C. elegans is a bacteriovorous soil nematode, P. pacificus is an omnivorous worm that is often found in association with scarab beetles. We found 20 Bacillus strains (consisting of B. cereus , B. weihenstephanensis , B. mycoides and Bacillus sp.) that were pathogenic to C. elegans and P. pacificus causing 70% to 100% mortality over 5 days and significantly affect development and brood size. The most pathogenic strains are three B. cereus ‐like strains isolated from dung beetles, which exhibit extreme virulence to C. elegans in less than 24 h, but P. pacificus remains resistant. C. elegans Bre mutants were also highly susceptible to the B. cereus ‐like strains indicating that their toxins use a different virulence mechanism than B. thuringiensis Cry 5B toxin. Also, mutations in the daf‐2 / daf‐16 insulin signaling pathway do not rescue survival. We profiled the toxin genes ( bcet , nhe complex, hbl complex , pcpl , sph , cytK , piplc , hly2 , hly3 , entFM and entS ) of these three B. cereus‐ like strains and showed presence of most toxin genes but absence of the hbl complex. Taken together, this study shows that the majority of naturally isolated Bacillus from soil, horse dung and Geotrupes beetles are benign to both C. elegans and P. pacificus . Among 20 pathogenic strains with distinct virulence patterns against the two nematodes, we selected three B. cereus‐ like strains to investigate resistance and susceptibility immune responses in nematodes.
Caenorhabditis
Cite
Citations (50)
Cite
Citations (873)
Caenorhabditis
Model Organism
Cite
Citations (15)
Ostertagia ostertagi
Hermaphrodite
Teladorsagia circumcincta
Cite
Citations (18)
1. In some overwintering insects, several authors have suggested a trade-off in the allocation of metabolic reserves between diapause maintenance and post-diapause reproduction. To investigate this trade-off, the diapausing larvae of the bruchid Kytorhinus sharpianus were exposed to various periods of chilling (5 °C) and we examined changes in egg production and adult longevity after the termination of chilling. 2. A relatively long period of chilling during diapause increased both the incidence and rate of diapause termination. 3. Long periods of chilling reduced egg production, and increased the preoviposition period, but they also increased the longevity of adults that had not fed. When the adults fed on sugar and water, the post-diapause females that had experienced 50 days chilling had significantly longer preoviposition periods and longevity than non-diapause ones but a significant difference was not seen in their egg production. 4. We discussed the physiological mechanism causing this phenotypic difference between the diapausing and non-diapausing generations by the double trade-offs in the allocation of metabolic reserves not only between diapause maintenance and reproduction but also between longevity and reproduction.
Cite
Citations (71)
Caenorhabditis
Lineage (genetic)
Hermaphrodite
Cite
Citations (270)
Mild deficits in mitochondrial function have been shown to increase lifespan in multiple species including worms, flies and mice. Here, we study three C. elegans mitochondrial mutants (clk-1, isp-1 and nuo-6) to identify overlapping genetic pathways that contribute to their longevity. We find that genes regulated by the FOXO transcription factor DAF-16 are upregulated in all three strains, and that the transcriptional changes present in these worms overlap significantly with the long-lived insulin-IGF1 signaling pathway mutant daf-2. We show that DAF-16 and multiple DAF-16 interacting proteins (MATH-33, IMB-2, CST-1/2, BAR-1) are required for the full longevity of all three mitochondrial mutants. Our results suggest that the activation of DAF-16 in these mutants results from elevated levels of reactive oxygen species. Overall, this work reveals an overlapping genetic pathway required for longevity in three mitochondrial mutants, and, combined with previous work, demonstrates that DAF-16 is a downstream mediator of lifespan extension in multiple pathways of longevity.
Mediator
Cite
Citations (144)
To analyze the relationship between resistance to oxidative stress and longevity, we isolated three novel paraquat-resistant mutants, mev-5, mev-6, and mev-7, from the nematode Caenorhabditis elegans. They all showed the Dyf (defective in dye filling) phenotype, but not always resistance to heat or UV. Life-span extension was observed only in the mev-5 mutant at 26 °C. These results indicate that longevity is uncoupled with the phenotype of paraquat resistance.
Cite
Citations (25)